Free Online Solvers
AMPL online : Create AMPL files off-line, then upload and solve them at this site. A variety of solvers can be selected, including MINOS, SNOPT, Lancelot and others. Limited to 300 variables and 300 constraints and 30 seconds of execution time.
NEOS: The Network-Enabled Optimization System. An online system for submitting and solving optimization problems including LP, MIP, NLP, etc.
Optimization as an Internet Resource: paper in pdf format that includes numerous useful links to web resources for optimization.
Wikipedia list of optimization software, some of which are free.
Free Student/Trial Editions of Commercial Solvers for LP/MILP/QP
Cplex: from IBM. Can also download the Optimization Studio for model creation. Associated free courses.
Gurobi: also includes a mixed-integer quadratic programming solver.
MOSEK: also has a very nice Matlab Toolbox interface.
XPress: includes a nonlinear solver.
Downloadable Modelling Systems That Include Free Solvers
AMPL: Student editions of the AMPL modelling system for various platforms. Demo-size editions of various commercial solvers are included in the download.
LINDO: Student editions of LP, NLP, and MILP solvers, plus the LINGO modelling language. Limited to 150 constraints and 300 variables. Windowed interface. The classic LINDO is easy to use and suitable for homework assignments. Look for it on the downloads page: a manual is also available there. Classic LINDO is not available for the Macintosh; Mac users should download LINGO, a system that includes a modelling language and associated solvers.
Maximal: Student edition of the Maximal Software modelling system (MPL) coupled with a student edition of the CPLEX LP/MILP solver. Windowed interface. Limited to 300 variables and 300 constraints.
Free and Open Source Linear Programming Codes:
COIN-OR: http://www.coin-or.org/projects/ has links to the CLP solver as well as many others for several classes of optimization problems.
GLOP is Google's open-source LP code.
Free and Open Source Mixed-Integer Linear Programming Codes
CBC: http://www.coin-or.org/projects/. CBC is a MIP framework that works with the CLP LP solver.
GLPK: http://www.gnu.org/software/glpk/glpk.html. MIP capability is built into GLPK. GLPK is also available embedded in Octave, a free and open source MATLAB clone, at http://www.gnu.org/software/octave/.
LP_SOLVE: http://lpsolve.sourceforge.net/. MIP capability is built into the LP_SOLVE.
MINTO: http://coral.ie.lehigh.edu/~minto/. MINTO is a MIP framework which requires that a separate LP solver be attached.
SCIP: http://scip.zib.de/. SCIP is a MIP framework which requires that a separate LP solver be attached. SCIP also incorporates many concepts from constraint programming.
SYMPHONY: http://www.coin-or.org/projects/SYMPHONY.xml. SYMPHONY is a MIP framework that works with the CLP LP solver.
Solvers That You May Already Have Access to:
LP, mixed-integer programming, and nonlinear solvers are included in software that you already have. You can find solvers in MS-Excel, Google Sheets, Matlab, and Octave.
See Hans Mittelmann's benchmarks comparing commercial and non-commercial solvers in many categories to find the one that will work best for you.
Tutorials, Textbooks, Problem Sets:
Optimization101.org (this site).
Advice on formulating linear programs by using building blocks called formulettes.
The linear programming FAQ page. Includes pointers to software, test models, etc.
The nonlinear programming FAQ page. Includes pointers to software, test models, etc.
The glossary of mathematical programming terms, many not found in standard dictionaries of mathematics.
Spreadsheet Optimization: By Frontline Systems, which markets add-in solvers for Microsoft Excel.
Optimization Modelling: By Maximal Software, which markets the MPL language and attached solvers.
Current as at March 10, 2021. Optimization101.org homepage.